Silicon is one of the most widely used materials in modern technology and can be considered as the backbone of the semiconductor industry. While micromachining and fabrication of microfeatures on silicon is critically important for various applications, the material's high hardness and intrinsic brittleness present significant machining challenges. It has been shown by previous studies that rotary ultrasonic surface machining can be effectively employed for brittle materials like silicon. However, micro-grooving using similar processes, which involves distinct material removal mechanisms due to high aspect ratios, has not been studied so far. To address this research gap, in this study, conventional micro-grooving (CµG) and rotary ultrasonic micro-grooving (RUµG) experiments have been conducted on silicon substrates at different feeding speeds to analyze the effects of ultrasonic vibration and processing parameters. The performance of both the processes has been evaluated based on a few key metrics, including cutting forces and edge chipping values. The micro-groove quality and material removal mechanism of those two processes have also been discussed to provide fundamental insights into process dynamics. It has been observed that better quality micro-groove is formed in the RUµG process, characterized by reduced cutting forces, minimal edge chipping, and enhanced groove wall quality.